This disclosure relates in general to copier/printers, and more particularly, to printing systems with multiple processing units providing substantial degrees of freedom in performing print jobs, and to print job scheduling for such printing systems.
Certain stocks, in particular heavyweight coated stocks, have greater fusing requirements than the majority of stocks. Current print systems when processing heavyweight coated stocks handle the greater fusing requirements is by increasing fuser temperature or by maintaining a constant fuser temperature for all stocks but reducing the process speed for heavyweight stock so as to provide increased fuser dwell time. These approaches are not ideal and require trade offs between equipment life and print process delays. Selective increases in fuser temperature leads to reduce fuser roll life and higher service costs, and print process delays with system productivity reduction while warming the fuser to prepare for difficult stocks. While a reduction in process speed reduces overall printer productivity by virtue of a slower speed through the fuser.
Adding to process delays, printing systems have generally employed only one or a few sheet paths, and only one or a few print job destinations. For example, a typical printing system may have a single printer or marking engine, which bottlenecks sheet processing down to a single print path. Even if multiple marking engines are provided, a print media conveyor may be configured to limit sheet processing to a single print path. In such an arrangement, the print jobs are queued and performed sequentially, in a first-in-first-out (FIFO) sequence. Some more advanced printing systems provide multiple sheet paths and multiple job destinations through concepts such as tandem printing or cluster printing when three or more printing systems are combined. In advanced multiple printing systems, the printing process is managed through a job scheduler that divides the sheets of a given print job amongst two or more of the linked printing systems. Each printing system of a multiple printing system is an independent printing system. There is a tendency to treat the greater fusing requirements as an issue handle by each individual machine.
For the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for processing of print jobs with stock having greater fusing requirements.